Gas-Graft Coverage After DMEK: A Clinically Validated Numeric Study

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Mathematical Modeling

Background:

• Descemet membrane endothelial keratoplasty (DMEK) is a surgical procedure to restore vision by replacing damaged endothelial cells.
• Achieving optimal graft coverage is crucial for successful DMEK outcomes.
• Bubble configuration and graft adherence are influenced by intraocular factors and surgical techniques.

Purpose of the Study:

• To investigate how patient positioning, gas fill volume, and anterior chamber size affect bubble configuration and graft coverage in DMEK.
• To develop and validate a mathematical model for predicting graft coverage in DMEK.
• To provide clinically relevant insights into optimizing DMEK surgical parameters.

Main Methods:

• A mathematical model was developed to simulate bubble dynamics and graft coverage in eyes with varying anterior chamber depths (ACD).
• Governing equations were solved numerically using OpenFOAM, an open-source computational fluid dynamics software.
• Numerical results were clinically validated to correlate gas fill with graft coverage.

Main Results:

• In phakic eyes (ACD = 2.65 mm), 70% gas fill significantly increased graft coverage (85-92%) compared to 35% fill (35-38%).
• In pseudophakic eyes (ACD = 4.35 mm), graft coverage with 35% fill ranged from 8-52%, increasing to 63-94% with 70% fill, with positioning playing a larger role.
• The model showed negligible differences between air and SF6, and identified thin aqueous humor patches within gas bubbles in some cases.

Conclusions:

• Graft coverage in phakic eyes is primarily determined by gas fill, with positioning having minimal impact.
• In pseudophakic eyes, graft coverage is dependent on both gas fill and patient positioning, with positioning becoming more critical as ACD increases.
• Anterior chamber depth significantly modulates the effect of patient positioning on gas bubble behavior and graft coverage post-DMEK.